In our pilot work, we have shown that a group of children fitting RDC criteria for major depressive disorder in adults, can be identified by structured interview. We propose to study in these children, psychobiological parameters which are known to be altered in adult depressive illnesses. This will be done in order to (1) validate the diagnosis of perpubertal depressive illness, and (2) establish its relationship to adult depressive illnesses. In order to meet this objective we will carry out longitudinal assessments of polygraphic sleep recordings, 24hr secretory patterns of growth hormone, cortisol and prolactin, and 24hr fractional excretory pattern of urinary MHPG. Such assessments will be carried out at three points in time: (2) while ill, medication-free (2) after 6 weeks on imipramine (3) on follow-up when clinically recovered and medication free. In an interlocking application being submitted simultaneously three other parameters are to be studied: response to imipramine, genetic family study and follow up.